The Triumph Dolomite Club - Discussion Forum

The engine I'm rebuilding has a high-lift cam installed. The engine was running ok the last time it was on the road but I noticed some small dings in the piston crowns when I stripped it. I would like to check the piston to valve clearance to be sure all is ok.

I know there are a couple of ways to measure this, one using clay, plasticine, putty or similar. I don't want to do it this way as it doesn't seem very accurate. I'd like to measure the valve lift with a dial gauge at TDC then measure again at the appropriate BTDC & ATDC. At what point (angle of the crankshaft) should I measure the inlet & exhaust valves either before or after TDC?

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Sprintless for the first time in 35+ years. ... Still Sprintless.

Engines, Gearboxes, Overdrives etc. rebuilt. PM me.


1997 TVR Chimaera 450

15 before and 15 after should be enough. If you are using light springs for checking you can also rotate the engine and press with your thumb to open the valve(s) to feel when they get close. Cam timing will obviously affect the clearances relative to btdc and atdc too

Tony

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Membership 2014047

Thanks Tony. I thought it was something like that. Yes, I propose to use some light springs so I can just press the valves down.

_________________
Sprintless for the first time in 35+ years. ... Still Sprintless.

Engines, Gearboxes, Overdrives etc. rebuilt. PM me.


1997 TVR Chimaera 450

Don't forget with the engine running and everything hot, especially at higher revs, the pistons will come up a couple of thou higher in the bore.

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Russ Cooper
Dursley
UK

Thanks Russ.

What would you guys recommend as a minimum clearance?

_________________
Sprintless for the first time in 35+ years. ... Still Sprintless.

Engines, Gearboxes, Overdrives etc. rebuilt. PM me.


1997 TVR Chimaera 450

Good question! Sorry I am not the best one to ask, I was just pointing out that what you measure on a cold dry engine will not stay the same when its running.

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Russ Cooper
Dursley
UK